Circuit breakers with magnetic blowout



Jan. 14, 1958 s. TESZNER CIRCUIT BREAKERS WITH MAGNETIC BLOWOUT Filed July" 1 1955 Unite States atent O CIRCUIT BREAKERS WITH MAGNETIC BLOWOUT Stanislas Teszner, Paris, France, assignor to Forges & teliers de Constructions Electriques de Jeumont, Paris,

rance Application July 1, 1955, Serial No. 519,580

Claims priority, application France July 16, 1954 9 Claims. (Cl. 200-147) This invention relates to circuit interrupters and more particularly to magnetic blowout, in which the disconnecting are, disposed between concentric electrodes, performs a rapid rotation within a narrow space defined by insulating members spaced close together. Several types of this device are described in the French Patents No. 693,293 of July 9, 1929, and No. 719,593 of July 3, 1931. However, none of these disclosed apparatuses has rendered entirely satisfactory results up to the present.

One of the principal reasons for difficulties experienced in their use is the fact that their disconnecting arc does not have either a desirable shape or length so that their complete extinction does not occur under the most advantageous conditions. Hence, the result is that the breaking force is very limited or that it becomes neces sary to use a plurality of interruption in series, which complicates the construction and presents insulation problems difiicult to solve in the case of high voltages.

The invention has as a principal object to eliminate these disadvantages and to construct simple and less cumbersome circuit breakers having the greatest possible assurance of operation at high voltages built into them as well as considerable breaking power.

Other objects are to provide a system of rotary arcs which secure within a short time a substantial elongation of the arcs resulting in their quick deionization; the

reduction in the wear of apparatus and the elimination of interfering gas-pressure.

According to the invention the breaking arcs are subjected to magnetic blow-out fields which are distributed in an appropriate way in order to displace their roots at angular velocities which are very unequal to effect significant elongations of these arcs within a minimum time. There are also provided means to cool the arcs by a good thermal contact with a narrow arc chute, to suitably shift the phase of the magnetic field and to eliminate the production of undesirable gaseous pressures which could slow down or stop the rotation of arcs as well as to suitably shift the phase of the magnetic blow-out fields in relation to the current flowing through the circuit-breaker.

Other characteristics and the advantages of the inventionare indicated by the description of the constructions, represented by way of non-limitative examples in the annexed drawing. In this drawing:

Fig. 1 is a schematic vertical section view of an interrupter unit according to the invention.

Fig. 2 is a schematic diagram of the connections.

Fig. 3 is a sectional plan view of an embodiment of the circuit-breaker which contains two interrupting members in series and Fig. 4 is a variant of Fig. 2.

In Fig. 1 there is shown in vertical section, an interrupting element which contains an internal ring-shaped conductor 1, forming the fixed electrode of the device and cooperating with a movable contact which may have the shape of an arcuate plate 2 carried by a pivoting .arm 3. The movable contact 2 is shown in its open posi- Fig. 1.

2,820,122 Patented Jan. 14, 1958 tion. When the circuit is closed, the end of contact member 2 is carried toward the ring 1 by the action of a spring 3A. The inner ring 1 is surrounded by an outer ring or electrode 4, provided with several apertures, particularly with an opening 5 allowing the movable contact 2 to pass therethrough. The concentric electrodes 1 and 4 are discontinuous having preferably a break 1A or 4A. These breaks or discontinuities are provided to avoid the undesired circulation of secondary currents which could be induced in the blow-out fields, described below.

The inner electrode incloses an axial core 6 terminated by two pole pieces 7 of appropriate shape and cross-section. Around the core 6 there is wound a blow-out coil 8, one end of which is connected with the inner ring 1 and the other, as shown in Figs. 2 and 3, forms an outer connection of the interrupting element.

When the circuit of the device according to the Fig. 1 is closed, the current which passes through the coil 8 produces between the two rings 1 and 4, a magnetic blowout field, which is substantially transverse to the plane of The distribution of this field which is determined by the size and shape of the pole pieces '7, is an important feature of the present invention.

According to one of the characteristics of the invention the pole pieces 7 disposed along the axis of the device are given a shape and size producing a reinforced field strength near the inner electrode 1 and a relatively reduced field strength near the outer electrode 4. This arrangement offers many important advantages in addition to a more effective utilization of the coil 8.

The inner root of the are which moves on the electrode 1 is propelled by an electrodynamic force which is larger than that acting on the outer root which is moving in the same direction on the electrode 4. Hence there results on the one hand a far greater difference in the angular velocities of both roots, i. e, a considerably greater extension of the length of the arc. Supposing, for example, that the intensity of the magnetic field at the outskirt, adjacent electrode 4, is always equal to unity, and that it attains the value of 3 or more in the vicinity of the electrode 1, then the dynamic curve of equilibrium of the rotating arc assumes a shape which is continuously growing longer, as represented by A or A respectively.

The invention has the following particular features:

(1) The are which is considerably longer turns between two insulated cold members lii and 11 which are spaced close together, as shown in Fig. 3 so that the arc is flattened and a better thermal contact is provided, whereby the arc is better cooled and deionized so as to be definitely extinguished.

(2) The various insulated mold members 10 and 11 are spaced at a uniform interval.

(3) Since the inner root of the arc leaves the contact zone between the ring 1 and member 2 more quickly, this zone remains colder and is used up far less rapidly.

(4) For the same reason, the re-striking of the arc is less probable.

All these advantages, whose importance is evident, bring about a considerable rise in the breaking power.

In order to interrupt high voltage circuits it is possible to establish a series of two or more interrupters of the kind depicted above. For example in Fig. 2 there are shown schematically two interrupters designated by A and B. Each of them is provided with a respective blowout coil, 8A and 8B, and a movable breaking electrode 2A or 2B, the latter cooperating with the corresponding inner electrodes 1. The connections 14 and 15 provided with fixed contacts 13A and 13B are connected by contacts of short circuit element 12A and 12B.

At the start of operation of the circuit-breaker, contacts 12A-.-13A and 12B13B are opened, whereby the blowout coils 8A and 8B are inserted in the circuit,

shown in Fig. 3. tprises short-circuit branches 12A and 12B cooperating -=with two principal fixed contacts 13A and 13B, and the whereupon the breaking contacts 2A and 2B are actuated and pull both blown arcs simultaneously. A disconnecting switch S is preferably provided to suppress electrostatic stresses in the opened device.

The required distribution of the magnetic blowout fields can beobtained, for example, if the pole'pieces 7 have suitable diameters, sizes and thicknesses. An excessive extension of the arc length must be avoided, because, in

fact, if the trajectory A is too long and occupies more than 360 degrees in the indicated interruption unit, there may arise the danger of restriking due to a too short distance between both ends of the arc. This must be taken into account when determining the distribution of the magnetic blowout field.

The movable contacts can have the form of two forks as One, called the principal fork, comother includes breakingbranchesZA and 2B cooperating with the two fixed electrodes or rings 1. If the circuitbreaker is closed, the current arrives'through the con- 8A, the ring 1, the branches 2A and 2B of the breaking fork and finally through the coil SE to the contact MB.

The principal fork is fittedwith a link mechanism of anyv suitable form. For example it. can be constructed as a shoulder 16 which is carried by an insulating stern 16A. Upon insertion of both interruption elements in the circuit, the piece 16 carries away at great velocity the breaking fork 2A2B, which is suddenly separated from the ring electrodes, striking the two arcs which rotate simultaneously and are blown by the coils 8A and 8B.

To exhaust the heat and the bases released by the said arcs, the narrow deionization chambers or are chutes are provided with ventilation means such as the draught chimneys or ventilation holes in the outer electrode referred to in the two aforementioned patents.

According to the present invention there are provided several orifices disposed close to the inner electrode i, as designated by 17 or 17A in Pig. 3; and several escape orifices 18 and 18A are provided on the outskirt of the interrupting elements.

The elongated rotating arcs of the described form act like the vanes of a centrifugal pump-in producing in the presence of the above openings a free centrifugal flow of fresh air inside of the interruption elements. Hence the high gaseous pressures which. may seriously brake the quick rotation of the arcs are eliminated; and this circulation efliciently contributes to cooling and to the definite extinction of the breaking arcs.

In the case of high voltages it is advantageous to direct the escaping ionized gases in such a way as to eliminate the possible striking of the outer arcs. To this end the escape apertures 18A of both interruption elements A and YB are preferably oriented in opposite directions, as shown,

and the apertures 18 are preferably disposed in different angular positions in order to be spaced far away each from the other, .contrariwise to Fig. 3 whereboth apertures 18 are shown in the same radial plan to simplify illustration.

The extinction of the arcs is improved by means of an impedance, such as a resistance R, represented in Fig. l and connected to complet for example, the secondary turn which is formed by the outer electrode 4. Thereby a secondary current which is induced in the element i produces a component of the magnetic field which is shifted by 90 electrical degrees in relation to the current ibeing' interrupted. This component has therefore acerttain=value when the current o'f the circuit -breaker and The insulating disks 10 and 11 of the arc chutes are arranged in such a way that they can be easily dismounted to facilitate maintenance and cleaning. Also there can be provided means which allow rotation of these disks from time to time in order to equalize their wear, if any.

As may be seen, the construction according to Figs. 2 and 3, involvesa disconnecting switch S which is installed to suppress electrostatic stresses in the device after opening its contacts. By modifying the contacts and the connections according to the Fig. 4, the opening is effected in three stages: first, the separation between the elements 13A and 12A which insert the blowout coils, is performed, whereupon the current passes through the fixed contacts 13B, elongated for this purpose, secondly, the blown break .is carried out by the displacement of the movable 'contacts 2A and 2B; finally, the separation effected between 13B and 12B secures a complete disconnection of the current.

It is to be noted that the fixed contacts and the mechanical system providedfor operation in the desired order can be locatedbetween the two breaking chambers or arc chutes A and B instead of being disposed externally thereof as shown in Figs. 2 and 4.

It is obvious that the embodiments which are describedcan be modified in different ways, especially, as to the shape and the structure of the disks, and the space separating them, as to the pole pieces, the arrangement of the mechanical system and other details of construction.

Regardless of these modifications, it can be seen that the means according to the invention provide circuit breakers with magnetic blowout having reduced dimensions. A great simplicity, good insulation and quick and .efiicient circuit breaking characteristics with a practically uniform distribution of thermal insulating partition walls of the arc chutes.

What I claim and desire to secure by Letters Patent is:

1. A circuit interrupting apparatus for interrupting electrical currents of relatively high potential and large current value comprising, two stationary, concentric spaced, substantially cylindrical, conductive electrodesginsulating members extendingtransversely of the longitudinal .axis of said electrodes and spaced providing relatively large, cooling and arc-deionizing surfaces cooperating with said electrodes in defining at least one narrow substantially confined space between adjacent insulating members; ci'rcuit interrupting means including means for establishing an arc between said electrodes; and means comprising electro-magnetic means for producing a magnetic field having thermal contact with the large deionizing surfaces so as to be readily extinguished.

2. A circuit interrupting apparatus according to claim 1, in which said concentric electrodes comprise split rings thereby precluding secondary currents from being induced in at least-the inner electrode when said arc -is established.

3. A circuit interrupting apparatus according to claim '2, including impedance means shunting the split in the outer ring electrode thereby to allow a secondary current to be induced in said outer ring electrode, said impedance means having a selected value for shifting the phase of said secondary current thereby to generate a phase-shifted component in said magnetic field and to maintain the rotation of the arc column by said component when the current being interrupted is passing through its zero value.

4. A circuit interrupting apparatus, according to claim 3, in which said magnetic field has a value for maintaining the leading end of the arc angularly spaced from the trailing end of said are thereby to preclude restriking the are.

5. A circuit interrupting apparatus according to claim 1, in which said insulating members are provided with apertures for venting gas pressure in said narrow space and disposed for cooperating with said rotating arc in establishing a centrifugal fresh air flow in said narrow space.

6. A circuit interrupting apparatus for interrupting electrical currents of relatively high potential and large current value comprising, two stationary, concentric, spaced, substantially cylindrical, conductive electrodes; at least two insulating discs extending transversely of the longitudinal axis of said electrodes and spaced providing relatively large, arc-cooling surfaces cooperating with said electrodes defining at least one narrow space between adjacent discs thereby forming a narrow circular arc chute, with the periphery of the inner electrode and means for moving said contacting means radially away from said inner electrode and for cooperating with said contracting means in establishing an are between said electrodes; and means including at least one coil for producing an electromagnetic field having a greater intensity close to the inner electrode than it has near the outer electrode, whereby the arc flattened by said cooling surfaces is stretched longitudinally by rotation on the surfaces of said electrodes at diiferent speeds and readily extinguished, the angular velocity of the arc root on the inner electrode surface being greater than the angular velocity of the arc root on the inner surface of the outer electrode, and said insulating discs having venting means for reducing gas pressure in said are chute.

7. A circuit interrupting apparatus according to claim 6, in which the insulating discs defining said are chute space are provided with apertures positioned to cooperate with said rotating arc to produce a centrifugal air flow in said chute for providing fresh air therein and for simultaneously venting gaseous pressures formed by the arc.

8. A circuit interrupting apparatus according to claim 6, in which said insulating discs are rotatably mounted thereby to allow selective rotation thereof in order to equalize their wear.

9. A circuit interrupting apparatus according to claim 6, in which said means for producing the electromagnetic field include means for rotating the arc roots at different angular velocities without the angular difference in positions of said are roots attaining 360 thereby precluding restriking the arc.

References Cited in the file of this patent UNITED STATES PATENTS 967,280 White Aug. 16, 1910 1,015,442 I-lixson Jan. 23, 1912 2,051,478 Hampton et a1. Aug. 18, 1936 2,109,226 Austin Feb. 22, 1938 2,150,564 Rowe Mar. 14, 1939 FOREIGN PATENTS 312,205 Italy Oct. 27, 1933 693,293 France Aug. 19, 1930 719,593 France Nov. 23, 1931 

